Fraction Calculator
Add, subtract, multiply or divide two fractions and get the answer simplified, as a mixed number and as a decimal.
How it works
a/b + c/d = (ad + cb) ÷ bd · a/b × c/d = ac ÷ bd · a/b ÷ c/d = ad ÷ bc
Adding or subtracting puts both fractions over the common denominator b×d before combining the tops. Multiplying is straight across — tops together, bottoms together. Dividing flips the second fraction and multiplies. The raw answer is then reduced by the greatest common factor of its top and bottom.
Worked example
1/2 + 2/3: the common denominator is 6, so it becomes 3/6 + 4/6 = 7/6. That’s already in lowest terms — as a mixed number 1 1/6, as a decimal about 1.166667.
Frequently asked questions
Why do fractions need a common denominator to add?
You can only count pieces that are the same size. Halves and thirds are different sizes, but both convert to sixths (3/6 and 4/6), and sixths add directly.
How do I enter a mixed number like 2¾?
Convert it to an improper fraction first: multiply the whole part by the denominator and add the numerator, so 2¾ = 11/4. The result panel converts back to mixed form for you.
Why does dividing flip the second fraction?
Dividing by a number is the same as multiplying by its reciprocal: dividing by 2/3 asks how many two-thirds fit, which is the same as multiplying by 3/2.
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This calculator is for educational purposes. Double-check important results before acting on them.